WUT! how is that american musle an olds 455 V8 bb or dodge 318 sb or chev 454 bb is american muslce not a 3 liter v6 1) its mad small 2) 3.0 lol how is that muscle? how bout 455 cubic inches = 7.8 liters and stroke it out to a 493 and 8.0 sound comes from the power (displacement of air) now giving urself a bigger exhaust to make ur engine sound bigger then it is is going to decrease backpressure. which could cause ur valves to float. it should be single exhaust pipe off the headers. ur best bet (if ur just doin the top end) is to lighten it up and use better durations on the cam then the stock one. or get a straigt 6